This is my first post on this forum, sorry if I’m in the wrong section

I have built a 3 axes 4 motors new cnc all in aluminum with a Chinese VFD (1.5kw, 13A, 400Hz, 120VAC input) and a Chinese water cooled spindle (800W, 400Hz, 24000RPM). I’m using Mach3 and the Gecko G540 controller. All my settings are for PWM.

All is working fine but the only problem I have is with the spindle calibration. I have checked the VFD and on local control when I press the RUN it goes up to 400Hz, 24000 RPM, and the voltage on the VR(+10V) terminal is 9.88v. On the G540 the voltage on terminals 7&8 varies depending on the speed I ask.

I input on Mach3 M3S6000 and the VFD shows 11300 RPM / 188Hz, the volts on G540 T7/T8 = 2.42v
I input M3S12000 and the VFD shows 15398 RPM / 256Hz, 4.81v.

I have been playing with all the Mach3 settings for about 2 weeks now with no success. I don’t want the VFD to be exactly on but right now the difference is way out.

Perhaps someone on this forum knows what I’m missing

Nicolas